AMERITRON AL-80A Manuel d'instruction - Page 2

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~LATION

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The AL-80A ventilationsystem has been designed and tested

to maintain tube seal temperatures safely below the tube

manufacturer's rating when operated withinour guidelines.

To insure proper ventilation in your installation, observe the

following:

1. Do not block or restrict the ventilation holes in the

cover.

2. The exhaust air flowis over 50 CFM. Do not "assist" the

air flowunless the fan used exceeds the AL-80Ablower

CFM by a factor of 2:1.

3. Do not mount additional fans on the AL-80Acabinet.

4. The exhaust air will become quite warm at high

power levels. Do not place any heat sensitive objects

in the exhaust air stream.

POWER CONNECTIONS

The AL-80Ais supplied with a NEMA 5-15P plug for 117VAC

operation. The AL-80A can be modified for 234 VAG opera-

tion. If you desire to make this modification, two jumper wires

must be moved to new locations on the terminal block. (see

illustration below) The terminal block is located on the left

side of the rear panel.

The wiring between the fuse box and the amplifier AC. outlet

must be No. 12 gauge or larger in order to supply the

cur-

rent required (15 amperes) without a significant drop in line

voltage. The 117V outlet should be fused for 20 amperes.

IOO

117 VOLT OPERATION

234

VOLT OPERATION

ALC

Use a shielded audio-type cable to connect the 0-20 volt

negative ALC voltage to the transmitter ALC input. Consult

the transmitter manual for proper connection details. The

amplifier must be properly tuned on CW before adjusting the

ALC.

Proper adjustment is achieved as follows:

1. Set the MULTIMETER switch to the PO position.

2. Set the transmitter audio control about 20% higher

than normal.

3. Speak into the microphone in a normal tone of

voice and observe the reading on the 0-2000 R.F.

Watts scale.

4. Adjust the ALC ADJ control on the rear panel until the

amplifier is not clipping on an RF scope.

5. If an RF scope is not available, adjust the ALC control so

the audio peaks do not exceed the single tone output of

1000 watts.

METERING FUNCTIONS

The AL-80A has two illuminated panel meters. The Grid Cur-

rent meter provides a continous reading of grid current. This

is an exclusive feature of Ameritron amplifiers. Grid current

will indicate proper operation of the amplifier better than any

other parameter. Do not exceed 200 mA on this meter dur-

ing operation of the amplifier. The other meter reads Plate

Voltage (HV), Plate Current (Ip), Peak R.F. Watts (PO) and

ALC. The functions are explained as follows:

PLATE VOLTAGE (HV): Read D.C. Plate Voltage on the

0-3500 Volt scale. This scale is 100 volts per division. Nor-

mal voltages are 3100 volts no load, 2700 volts full load.

PLATE CURRENT (Ip): Read Plate Current on the 0-700 mA

scale. This scale is 20 mA per division. The average

operating current rating of the 3-500z is 400 mA maximum.

PEAK R.F. WATTS (PO): Read Peak R.F. Watts on the

0-2000 scale. The scale has 50 watt divisions below 1000

watts and 100 watt divisions above 1000 watts.

ALC: In this position the meter indicates the ALC detector

voltage. It provides a relative drive level indication of 200

watts full scale. The approximate drive level (average, not

PEP) can be estimated by dividing the Peak R.F. Watts scale

by 10.

IMPORT ANT

Do not make any modifications to the AL-80A cir-

cuit before checking with our engineering staff.

Improper changes may damage the AL-80A'and void

the warranty.

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